1. Field of the Invention
The present invention relates generally to the field of vehicle electrical system design. More specifically the present invention relates to a battery charging apparatus for vehicles for capturing some of the energy normally dissipated as heat in the wheel bearings or brakes during vehicle deceleration.
The apparatus includes an electric generator having an armature (stator) assembled onto, and a field structure (rotor) built around, the vehicle drive shaft. The generator is electrically connected to a transformer such as a conventional battery charger through a generator circuit which is in turn connected to the vehicle battery. The generator circuit includes a generator disengagement switch which is mechanically connected to the vehicle accelerator linkages to open the generator circuit when vehicle motor or engine power is being delivered to the vehicle wheels. This feature prevents expenditure of fuel energy to power the generator, so that only otherwise wasted energy is captured as the vehicle slows.
The generator floats vertically within a generator support structure fastened to the frame of the vehicle, includes a brace member extending from underneath the generator and having a resilient vertical biasing element for applying force upwardly against the generator to reduce the slight downward bowing of the drive shaft. The word "generator" is used in a broad sense throughout this specification and the claims to mean either a generator, an alternator or equivalent mechanism.
2. Description of the Prior Art
There have long been engine mounted generators for charging automobile and truck batteries. These most often have been mounted on brackets extending from an internal combustion engine and driven by a pulley drivably connected to the engine. A problem with this design is that it creates a drag on the engine as the engine is driving the vehicle wheels, and diminishes engine power and fuel mileage. Furthermore, such a generator would be of no value on an electrically powered vehicle, because net battery charge would be reduced if the generator were driven by the vehicle electric motor as the motor draws power from the batteries being charged.
Generators operated by vehicle drive shaft rotation are found in the art. Yet these generators operate whenever the vehicle is moving, so that while some wasted energy is captured during deceleration, useful energy is also lost during acceleration and speed maintenance. These prior generators also lack satisfactory and adequately explained generator support structures permitting the generator to rise, fall and vibrate with the vehicle suspension.
Farrell, U.S. Pat. No. 5,323,737, issued on Jun. 24, 1994, teaches an electric charging system for an electrically powered vehicle. An oscillating piston engine provides the motive power to drive an alternator connected through an input shaft to a variable transmission which is connected to a crankshaft. The electric power generated by the alternator charges two banks of batteries, each of which powers electric motors to drive each vehicle wheel.
Heidi, et al., U.S. Pat. No. 5,247,637, issued on Oct. 5, 1993, discloses a hybrid-propulsion vehicle having a front axle driven by an internal combustion engine and a rear axle driven by a first electric motor. The first electric motor is constructed around and delivers torque to the drive shaft just forward of the differential housing to drive the rear axle. This first motor always functions as a motor. A second motor is mounted on the engine itself in the conventional alternator location, and operates as a generator under certain conditions. No generator on the drive shaft is provided, and the hybrid drive construction does not seem suited to gathering wasted vehicle energy. Another hybrid propulsion vehicle is disclosed in Moroto, et al., U.S. Pat. No. 5,513,719, issued on May 7, 1996. A generator is drivably connected to an internal combustion engine output shaft, but is separate from the shaft and located within the engine compartment.
Medina, U.S. Pat. No. 4,579,955, issued on Apr. 1, 1986, reveals an automotive power plant. Medina includes an electric motor with a motor drive shaft extending to the transmission. The transmission has an output drive shaft connected to a vehicle differential for driving one or a pair of the vehicle wheels. A battery pack is connected to the electric motor by leads. A generator control switch is connected by a lead to the stator of a generator adapted to deliver power to the battery pack. The electric motor accelerates be vehicle to a certain speed, and then the power plant switches the drive to an internal combustion engine. The generator recharges the motor batteries while the internal combustion engine drives the vehicle. Vehicle kinetic energy is not selectively captured and transformed into electric energy. An electric motor is provided on the rear axle, but not the generator.
Kawamura, U.S. Pat. No. 5,432,383, issued on Jul. 11, 1995, teaches an electric generator system driven by a gas turbine to supply electricity for propelling an electric motor vehicle. Electric generators are mounted on the turbine rotatable drive shaft which is driven by combustion gas energy, so that the output power of the turbine is divided and borne by the electric generators. Depending on the rotational speed of the vehicle wheels, the electric generators are selectively operated and the generated electricity is supplied to the wheels.
Yang, U.S. Pat. No. 5,489,001, issued on Feb. 6, 1996, discloses a differential coupling and compound power system for a hybrid driven vehicle. A magnetic coupling and driving device are driven by the engine output shaft to act as an alternator for charging the battery of the vehicle. The magnetic coupling can also act as a motor to drive the vehicle while receiving power from the battery to drive the vehicle in unison with the engine. The magnetic coupling can also act as a vehicle brake. Yang states that its differential coupling and compound power system produce a hybrid electric vehicle in which the size of the engine can be minimized and can operate at a constant speed or a partially modulated speed to lower pollution effects, and that any associated reduction in power output is to be supplemented by the magnetic coupling and driving device. When the vehicle is braking, the magnetic coupling and driving device is capable of solely driving the vehicle, and also of providing initial torque to the engine to start the engine. Consistent and selective use of the magnetic coupling and drive device to gather wasted deceleration energy is not disclosed.
Additional art includes Cullin, U.S. Pat. No. 4,663,937, issued on May 12, 1987, for an electro-mechanical-hydraulic power generating system; and Jeanneret, U.S. Pat. No. 5,402,046, issued on Mar. 28, 1995, for a vehicle drive system in which a generator is connected to an engine by means of a gear train.
It is thus an object of the present invention to provide a battery charging apparatus which converts vehicle kinetic energy normally lost during braking and other vehicle deceleration into electric energy and for transmitting this electric energy to the vehicle battery.
It is another object of the present invention to provide such an apparatus which gathers energy from the vehicle drive train, and specifically from the drive shaft, and includes a generator within a generator support structure which permits the generator to float vertically with the vehicle suspension system.
It is still another object of the present invention to provide such an apparatus which is suitable for use on electric motor powered vehicles.
It is finally an object of the present invention to provide such an apparatus which is economical to manufacture and reliable.